1. Field of the Invention
The present invention relates to a circuit arrangement for time-division multiplex telecommunication exchange systems, particularly pulse code modulation (PCM) telephone exchange systems, comprising time-division multiplex lines on which a plurality of time channels form a time-division multiplex, and on which different, successively following time slots are assigned to the time channels, and on which the time slots are arranged in pulse frames. In addition the respectively same time slot is assigned to each of the individual time channels in the various, successive pulse frames. Time-slot multiples equipped with information memories and holding memories are provided by way of which time channels on a time-division multiplex line connected at the input can be individually switched with time channels of a time-division multiplex line connected at the output. The arrangement further comprises a respective signal channel per time-division multiplex and serving as one of its time channels for the transmission of switching identifiers individually assigned to the remaining time channels, the time slots of the signal channel being combined over a plurality of pulse frames into pulse frames which, just like the pulse frames, successively follow one another. Super pulse frame time slots within a super pulse frame are assigned to the remaining time channels which serve as connection-associated message channels. Information memories are provided in wich, on the one hand, the write operation is sequenced in accordance with information memory element addresses stored in the holding memory, the holding memory being cyclically read in accordance with the successive time slots of the channels of the input time-division multiplex lines and, on the other hand, the read operation is cyclically sequenced in accordance with the successive time slots of the channels of the output time-division multiplex lines.
2. Description of the Prior Art
In time-division multiplex telephone systems as are described, for example, in the periodical "Telcom Report," Vol. 4/1981/Supplement, fully incorporated herein by this reference, a respective common signal channel is provided for a plurality of time channels, for example, for 30 time channels. The signal channel serves for the transmission of signaling informatin in individual assignment for each of the remaining (30) time channels which can be individually and selectively utilized as message channels for the completion of individual connections.
In a generally known manner, the sub-information transmitted over a time-division multiplex line and individually corresponding to the time channels are ordered in pulse frames. A pulse frame always comprises a series of sub-information of which each is respectively assigned to a time channel. One of the sub-information is assigned to the signal channel. Since the sub-information assigned to the signal channel within a single pulse frame would not suffice in order to signalize the individual switching identifiers of the message channels for the remaining time channels of the appertaining time-division multiplex line serving as information channels (cf. German Letters Pat. No. 1,910,974, corresponding to British patent specification No. 1,263,006, both of which are fully incorporated herein by this reference), the sub-information corresponding to the signal channels are combined over a plurality of pulse frames into super pulse frames within which the chronological position, i.e. the chronological relationship to the respective beginning of each super pulse frame, individually specifies the assignment of a sub-information to one of the remaining time channels employed as message channels. For this purpose, the sub-information assigned to the signal channel within a respective pulse frame can be assigned to one each of the remaining or to two or more of the remaining time channels of the appertaining time-division multiplex line employed as time channels, or, on the other hand, the sub-information within two or more successive pulse frames can be assigned to one each of the remaining time channels. Generally, the sub-information lying within a single pulse frame and assigned to a signal channel is sub-divided into two parts with the same respective plurality of bits, of which each respective part is individually assigned to one of the remaining time channels, i.e. one of the time channels serving as message channels.
In time-division telephone exchange systems (for example the periodical "Telcom Report" Supra), it is standard to accept the signaling sub-information assigned to the time channels of each of the time-division multiplex lines and serving for the signaling of switching identifiers with the assistance of the decentralized control device of a terminating group (LTG) (the same applies to analog trunk lines and to analog subscriber lines) and to forward them to a central control unit. This process is the signaling sub-information and designationally feeds them to those decentralized control devices of those terminating groups by way of which those connections were forwarded which extend over the time channels belonging to the time-division multiplex line.
In order to significantly reduce the considerable control unit load which occurs from the mere switching identifier forwarding by means of signaling sub-information which are always to be taken by the terminating groups from that time channel of each of the time-division multiplex lines serving for the signaling of switching identifiers and, subsequently, are to be resupplied to each of these time channels according to the exchange data of each individual connection of all through-connected connections, an arrangement was created according to the aforementioned German Letters Pat. No. 1,910,974 which, for the purpose of switching sub-information serving for the signaling of switching identifiers from a switching matrix for the through-connection of message connections ("connection switching matrix"), additionally provides a further switching matrix ("signal switching matrix") for the through-connection of such connections via which the sub-information corresponding to the message connections and serving for the signaling of switching identifiers can be switched. This circuit arrangement is based on the fact that each of the sub-information is provided with a respective assignment information which specifies the assignment to the respective message time channel.